Northwest Coastal

A significant storm this weekend will result in another major avalanche cycle.

Good - -1

An intense storm with a southern moisture feed (a Pineapple Express) is due to hit this region this weekend, bringing 10-20 cm new snow on Saturday and 20-30 mm rain on Sunday. Freezing levels should start out around 700 m Saturday and spike sometime Saturday night/Monday morning to as high as 2000 m. Winds through this storm will be extreme southwesterly. Flurries may continue into Monday, freezing levels will gradually lower to valley bottom by the end of the day.

Several relatively harmless (size 1) human-triggered avalanches were reported to have occurred in the storm snow at treeline elevations on Thursday. On Wednesday, a natural avalanche cycle up to size 3 occurred affecting all aspects and all elevations. Along Bear Pass, 90% of the avalanche paths were reported to have run.

A significant storm dropped 40 to 80 mm of precipitation on this region since Tuesday bring treeline snowpack depths into the 3-4 m range. The storm was accompanied by high winds and touchy fresh wind slabs and storm slabs now exist as a result. A rain crust formed below about 1000 m, which is not lightly buried with new snow. With all the new snow, earlier weak layers are getting rapidly buried to the point where they are hard to trigger. A relatively thin layer of surface hoar or facets was reportedly buried New Year's day - this may have been the focus of some of the storm snow releases during the current storm; however, I suspect this layer will settle out quite rapidly. Lower down, it is still possible to find a surface hoar/crust/facet combo from mid-December. I suspect it would take a very heavy trigger such as a cornice fall to trigger this layer now, although if you are traveling in an unusually shallow snowpack area I'd still be cautious of it. The lower snowpack is generally well settled and strong.